1. Field of the Invention
The present invention generally relates to patient support devices and more particularly to an improved mattress which is selectively regionally inflatable by the patient.
2. Prior Art
The problem of bed sores developing in patients lying for extended times on hospital beds is substantial. The problem is particularly severe in cases of patients in immobilized or comatose conditions due to surgery, injury and/or old age. In order to avoid bed sores in such circumstances, it is necessary to manually move the patient frequently to allow access of air to various parts of the patient's skin and to relieve continued pressure against those skin parts. This necessarily involves a considerable amount of time and cost on the part of hospital and nursing home personnel.
The bed sore or decubitis ulcer problem has been addressed recently by a number of inventions which involve the use of fluidfilled mattresses, which can be periodically inflated and deflated to intermittently support the patient at different points of the body, thus allowing periodic reduction of skin pressure and access to air. For example, U.S. Pat. No. 3,199,124 is directed to an air mattress which has a plurality of tubes extending the full length of the mattress and which form two alternating sets. The tubes of one set are all inflated to the same pressure while the tubes of the other set are all deflated. Thus, the two sets alternately inflate and deflate in order to reduce the chance of bed sores. Unfortunately, the use of such a mattress does not eliminate the bed sore problem, particularly because the patient may move slightly and in so doing, recompress a skin area which has just been relieved of pressure by the deflation of a tube previously lying under the patient. The inflation and deflation cycle is usually controlled in an automatic manner without reference to the position of the patient. Moreover, the pressure in the tubes is uniform throughout the length thereof and does not address the main problem which arises with such patients, because of the concentration of skin pressure in the bony back, hip and upper thigh regions where most of the patient's weight is supported. Decubitus ulcers may extend down through the skin right to the underlying bones.
U.S. Pat. No. 4,267,611 is directed to an inflatable mattress formed of two sets of tubes which are alternately inflated and deflated. The sets alternate with each other in position and are generally transversely disposed across the mattress. Those tubes are also of generally uniform thickness and support area except at the foot of the mattress. A similar transversely extending dual set of tubes of uniform size and length is disclosed in U.S. Pat. No. 2,998,817. U.S. Pat. Nos. 3,705,429 and 4,391,009 also disclose transversely extending sets of tubes of generally uniform size and length but of more complicated design than in the previously described patents. Even more complicated is the mattress configuration described in U.S. Pat. No. 4,279,044, which configuration is difficult to manufacture, repair and utilize. U.S. Pat. Nos. 3,740,777 and 3,000,539 disclose more exotic versions of body support systems.
All of the above-described devices fail to specifically treat and deal with those areas of the mattress upon which the main support points of the patient lie and also fail to deal with the likelihood that the patient may shift weight intermittently while lying on the mattress. Accordingly, the described devices fail to wholly eliminate bed sores in those patients most subject thereto.
U.S. Pat. No. 4,468,824 discloses an inflatable mattress which has a rectangular central area in the form of an opening or cavity totally devoid of patient support and positioned such that the main pressure areas of the patient, namely the lower back, hip and upper thigh, would be positioned over this cavity, thereby eliminating bed sores in this area. However, the mattress provides no physical support where it is most needed and therefore is totally impractical. Moreover, those areas of the patient's body bordering the cavity actually build up excessive pressure because they must serve as a support for the otherwise unsupported areas, overlying the cavity. Accordingly, danger of decubitus ulcers in those border areas is increased.
Accordingly, there is a need for an improved bed patient mattress which will essentially eliminate the development of bed sores or decubitis ulcers in patients who are most subject to the same. Such device should be simple and inexpensive to construct, use and repair and should also provide optimal physical support, regardless of whether the patient remains totally immobile or shifts his or her weight around on the mattress.